Metal panel roofs have become common architectural features for buildings, particularly large warehouse, retail, and convention type edifices. Such a roof is both aesthetically pleasing and functionally important to protect from natural elements, such as wind, rain, snow, and sun, and to enclose the subject building interior for environmental controls (such as temperature and humidity). Such metal roofs are also typically designed to allow for expansion and contraction due to outside temperature changes and generally constructed to ensure continued engagement of individual panels during long-term exposure to such natural elements. The panels are long strands of metal that are configured to permit engagement of different panel ends together with subsequent seaming (compressing, generally) of the engaged ends to create a resilient connection and seal from water and wind ingress. Additionally, such roof structures are typically pitched to a certain degree to effectuate water runoff as needed or properly sealed with gaskets to prevent ingress of moisture during such weather.
Wind uplift has been a major concern for seamed metal roof structures, particularly in climates that regularly exhibit such environmental phenomena. As the typical metal roof is pitched to form a peak, wind that traverses such a raised level potentially creates reduced pressure areas thereabove, resulting in a pressure differential both above and below the roof itself. Such a pressure differential thus may cause an uplift force on the individually connected panels, thereby jeopardizing the overall integrity of the entire roof, not to mention potentially compromise the seams between panels to possibly create undesirable and costly leaks. Wind damage has led to costly repairs and/or total replacements of such roof structures as well.
As noted above, typical metal roofing structures for such buildings include a plurality of parallel lengthy panels with complementary male and female edges for attachment (and seaming) with similarly configured adjacent panels. Such a continuous structure of seamed panels is also attached to an underlying edifice structure that includes purlins, joists, and bars; strong pins and/or clips, and like devices, permit strong attachment of the individual panels to the base structure.
The typical construction method thus includes the placement of a first panel atop a building purlin and permanently attaching the panel to the underlying structure as noted above. Clips and/or through-fasteners (i.e., sheet metal screws) are generally utilized to also attach adjacent roof panels to affix the panels to the building substructure and typically bear a significant amount of wind uplift forces by preventing differential movement between the panels and the support structure. However, the initial protection from high wind conditions is highly dependent on the overall structure of the seamed roof system itself; if the seams are sufficiently strong to permit the roof to remain intact upon exposure to high wind forces, the reliance upon stronger or more numerous clips for overall strength can be diminished. Thus, the provision of extremely strong and reliable roof panel seams would create a desirable wind-resistant multi-panel roof structure.
Typical roof panels include opposing female and male end flanges in complementary shapes to one another with each end portion configured in a manner that is ultimately perpendicular in relation to the roof surface itself. Thus, upon seaming of the two end portions, the finished seam between the two complementary end flange (portions) is standing from the roof surface with the actual seam engagement occurring on either side of the standing portion. In such a manner, the finished standing seam has two metal portions attached together, albeit with the actual engagement points existing on just one side of the standing portion. Basically, the previous roof panels included a female end flange portion that merely covered the male end flange portion of a different roof panel upon seaming. The typical female end flange would exhibit a standard u-shaped configuration while the typical male end flange would be roughly L-shaped to fit easily within the U-shaped receptacle female end portion. Upon seaming, the standing seam would thus be L-shaped to permit the free end of the female U-shaped end portion to fold underneath the L-shaped male portion, leaving a relatively strong seam but engaged in such a manner on one side of the shared standing seam portion of the two roof panels.
This configuration provides an effective strength to retain the overall roof structure in ambient environmental conditions, as well as a certain degree of wind uplift withstanding capabilities. Unfortunately, however, the wind updraft resistance exhibited by such typical roofing systems are limited to the strength of the one-sided standing seams themselves. If such seams loosen and/or the connected panels become detached, individual panels may then disassemble from the overall roof structure, thus compromising the entire roof in terms of environmental protection capability. The single-sided seam provided by these previous, typical roof panel configurations are limited in their potential to prevent panel detachment due to wind uplift; if one panel (such as at one edge of the entire roof structure) becomes detached, any lift movement of such a panel would invariably loosen the overall seam present with the adjacent panel, thereby reducing the reliability of such a seam to retain the edge panel in place. In effect, the unwanted lift and loosening of a panel and its seam could then result in a domino effect of further panel detachment, depending on the degree of continued wind uplift thereafter. If one panel becomes detached in this manner, however, the roof itself would most likely fail to prevent environmental problems inside the target building as the ingress of moisture, air, and any other undesirable consequences would occur.
Furthermore, the ability to increase the strength of an entire roof panel system in terms of wind uplift resistance, at least, could be affected through the increase in connection clips or other points of attachment to a building skeleton. However, such a situation creates a situation where increased labor and cost would be necessary to ensure such a result. Of additional consideration, however, is the possibility that a loosened seam connection would not only result in panel detachment, potentially, but also, even with extra points of panel attachment in place, a compromise in seam integrity to the point that moisture, air, etc., ingress would potentially occur at the adjacent panel connection points themselves, even if the panels were still in place. Proper moisture barriers (and other manners of preventing environmental damage through small openings within a roof) are of enormous importance, thus, to the utilization of such a multi-paneled roof system. With a single-sided seam in place, the possibility of seam disintegration is increased after time passes and continued environmental exposure occurs.
Additionally, such roofing systems generally require reliability in terms of permitting a person to traverse the entire roof for repairs, inspections, or any other necessity that requires such a presence. With a single-sided seam, it has been realized that uneven distribution of strength for the individual panels is exhibited in relation to a particular seam and the specific place a person may actually step on such a roof. In other words, since the torque applied to a roof surface differs from one area to another dependent upon the placement of a single-sided seam (i.e., on the side on which the seam is present, there will be more “give” in the roof panel, on the side on which the seam is not present, the roof panel will exhibit less “give”, thus exhibiting an overall uneven distribution in panel strength), a person trying to traverse such a roof will face areas of uneven resistance to the force applied due the person's weight and movement. Such an uneven distribution may thus create a situation wherein traversing such a roof may be a danger to the person as hazards such as falling and/or tripping may be prevalent with an uneven surface. Furthermore, the application of forces through weight distribution and movement may also contribute to the weakening of a single-sided seam as greater tension on the seam itself may occur that will degrade over time and upon continued application of such forces, much like the wind uplift forces as discussed above.
Thus, a need exists to provide a roof panel system that compensates for the need to reduce labor costs and time through utilization of limited numbers of clips for attachment of panels to purlins and joists, as well as that increases the strength of seams present between adjacent connected panels, and accords both an increase in uplift wind resistance of even distribution of tension strengths on either side of a standing seam. To date, the typical roof panel systems fail to provide such a benefit, but rely on standard techniques of single-sided standing seams through complementary female and male configured end flange portions to that end.